With Marlize's help, Barry tries to make a last-ditch attempt to reach the good DeVoe inside of the Thinker... and meets an old friend.

Thinker gathers the final component in his master plan, and to stop him Barry must train Cisco and Caitlin how to function in Flash Time. However, he refuses to endanger more of his friends. Meanwhile, Harry has an idea as to where they can find Marlize, and Cecile's pregnancy has strange side effects on her telepathy.

When they need an organic weapon to use against Thinker, Team Flash turns to Amunet... but Caitlin has an ulterior motive. Meanwhile, Cisco forms a "Council of Harrisons" after the Council of Wells kicks Harry out of the group.

Thinker continues with his "Enlightenment", and Gypsy joins Team Flash to try and stop him... and to discuss her relationship with Cisco.

While Harry discovers the results of the Thinking Cap overload on his mind, the rest of the team call on a former ally to help them transport Fallout away from Thinker.

Team Flash tracks down the last bus meta, Edwin Guass, and discover that he holds the key to defeating Thinker. Meanwhile, Ralph considers taking extreme measures against Thinker,

The Mechanic discovers what Thinker has been doing to her, and Breacher comes asking Cisco for help. Meanwhile, Team Flash goes after Subject 11, who can control gravity, and Barry questions if Ralph takes anything seriously.

Iris accidentally takes Barry's speed when a new meta with the power to swap powers touches both of them. Now they have to learn how the other half lives as Iris takes to the field and Barry monitors events. Meanwhile, Ralph refuses to leave S.T.A.R. Labs for fear that Clifford will kill him, and Harry undertakes a dangerous experiment to match their opponent's augmented intellect.

A terrorist detonates a nuclear bomb, and Flash must race between microseconds to try and stop it. Jesse and Jay lend their speed to his efforts, but even the three of them aren't fast enough to stop a nuclear explosion that has already happened.

The team discovers the identity of the ninth bus meta, but she doesn't want their protection. Meanwhile, Cecile turns to Harry for help when Joe's dreams keep her awake at night.

When Wolfe offers Barry and the bus metas to Blacksmith, Barry engineers an escape for all of them. Meanwhile, Ralph has a crisis of faith when an old "friend" tells him that he eventually fails everyone who counts on him.

The team goes after a meta with the power to shrink people and objects... and Cisco and Ralph ended up reduced to two inch height. Meanwhile, Barry tries to give Big Sir hope that they can clear his name.

While Barry sits in prison, Ralph faces his first major supervillain and is injured for the first time. He has second thoughts about being a hero, and turns to Barry for advice.

While Barry stands trial for Clifford's murder, a new meta threatens Central City and only Flash can stop him.

Iris has to choose between her husband and her friend when Amunet abducts Caitlin while Thinker captures Flash. Meanwhile, Caitlin meets a new metahuman, and Thinker unveils the next stage of his plan.

While Flash, Arrow, White Canary, Firestorm, and Alex attempt to return to Earth-1, Felicity and Iris team up to free Kara before Eobard and Fuehrer Queen remove her heart and transplant it into Overgirl.

Barry risks his career and his team trying to confirm that Clifford DeVoe is their unseen adversary. Meanwhile, the origin of the Thinker is revealed.

Flash and Elongated Man team up to fight one of the Thinker's metas, a Sioux Indian woman calling herself Black Bison that is hunting down the three pieces of an artifact. Meanwhile, Harry calls together three of his counterparts to form the "Council of Wells" and figure out who DeVoe is.

The guys and girls throw separate parties for Barry and Iris. While Barry gets drunk with some help from Cisco and Ralph takes them to a strip club, the ladies get involved with Killer Frost when her former boss, Amunet, demands that Killer Frost return to work for her.

While looking for the bus passengers, Barry and Joe come across Ralph Dibny, a former cop who was fired from the force and gained a.... unique power from the dark matter. Meanwhile, Gypsy's father Breacher comes to see his daughter's new boyfriend Cisco, and soon starts hunting him.

The team goes up against the second of the Thinker's metas: Becky Sharpe, aka Hazard, who can gain good luck for herself as long as everyone else suffers. Meanwhile, Cecile suggests to Joe that they buy a new house, and Iris tries to plan the wedding.

Barry and Iris discover that they're having communication issues and go in for couples therapy... just as a new meta starts targeting tech billionaires. Meanwhile, Cisco inadvertently blows off a special day for Gypsy.

Cisco comes up with a way to bring Barry back from the Speed Force when a new villain challenges Flash to a fight. However, Barry is... different than when he went in.